tvanlant

iTrader: (4)

I've been trying to troubleshoot an a/f imbalance with my car.
I'm using a holley dominator with wideband in each header collector.

The problem is that passenger's bank is 1.5-2.0 points leaner than the driver's bank (ie 16.5 vs 14.5 cruising, 13.5 vs 11.5 wot).
I've tried switching the O2 sensors and coils side to side, new plugs, new wires, but nothing changes. The lean bank stays with the passenger's side.

This would suggest I have a mechanical issue causing one bank to read lean (or possibly one bank to read rich).

Anyone have any suggestions on what to look for that could be causing this imbalance?

redtan

iTrader: (5)

Sounds like some sort of vacuum leak allowing unmetered air into that side of the engine and thus leaning out the AFR value. That or one or more injectors are partially stuck closed and not providing that side with the adequate fueling.

tvanlant

iTrader: (4)

Is there a vacuum source that could only leak one bank?
I've thought about an injector issue, but the engine isn't missing and runs completely smooth, so I don't think it's a spark or injector issue.

redtan

iTrader: (5)

Could be right around the manifold runner where it meets the heads. Also injector doesn't have to necessarily be completely stuck and thus make the car run badly or noticeable. It could be that it's partially stuck and only delivering a portion of the fuel needed. The engine can run perfectly smoothly with less fuel at 16.5 AFR so you definitely won't see a missfire at that point.

In the end it's something simple to think about, it's either a fuel or air related issue. Whether too much of one or too little of the other. Now start going over the parts of the engine that are dealing with delivering air and fuel to the combustion chamber. Anywhere along that path will be your issue. The good thing is you don't have to go too far back because your issue is only on one bank...so whatever the problem is is close to said bank otherwise it would affect both.

mrvedit

An exhaust leak can also throw the WB values off.
A misfire will give a very lean value in that bank (lots of unused O2).
I also have two WB gauges and logging - one for each bank. It drives me crazy when they are different, but mine are currently only about .5 different at cruise and sometimes a bit more at idle. My previous completely different LS2 engine was like that too - I suspect that on the average car they are more different than some people might expect, especially with big injectors.
However a difference of 2.0, especially at WOT is way too much. I don't think a vacuum leak would have any effect at WOT - heck there is no vacuum.

I didn't read that you have switched injectors right to left; that might isolate the problem.

I recently had a stuck injector from a brand new set. I found it by using an Infrared thermometer on each header tube.

tvanlant

iTrader: (4)

I checked headers for leaks. I even bought a smoke machine and smoked both headers and the intake manifold and didnt find any leaks.

I will try the injectors next. If an injector were stuck though, wouldnt it make the engine mis? It runs perfectly smooth

redtan

iTrader: (5)

No like I said before, it could be partially stuck or clogged and only able to deliver enough fuel for 16.5 AFR at idle. That is still enough fuel to fire off properly and run the engine smoothly, but not enough fuel to be at the proper fueling.

tvanlant

iTrader: (4)

All cylinders are 150 compression except for #1, which is 135.

Think #1 cylinder is a problem?